The base clock speed for DDR4 RAM is typically between 800 and 1600 MHz, with a voltage requirement of 1.2 V. Some manufacturers may offer overclocked RAM with speeds rated over 2400 MHz, which can be accessed by enabling the RAM’s XMP/DOCP profile.
DDR4 operates at a voltage of 1.2 V with a frequency between 800 and 1600 MHz (DDR4-1600 through DDR4-3200), compared to frequencies between 400 and 1067 MHz (DDR3-800 through DDR3-2133) [a] and voltage requirements of 1.5 V of DDR3
DDR4 SDRAM - Wikipedia
By default, the maximum stock clock speed for DDR4 RAM is 2400 MHz. When you see RAM with speeds rated over this, it means the module has been overclocked to that speed by the manufacturer.
To access the RAM’s boosted clock speed, you must first locate and enable the RAM’s XMP/DOCP profile.
What You Need to Know about RAM Speeds - Is Faster RAM Worth It?
Double Data Rate Synchronous Dynamic Random-Access Memory is a double data rate (DDR) synchronous dynamic random-access memory (SDRAM) class of memory integrated circuits used in computers. DDR SDRAM, also retroactively called DDR1 SDRAM, has been superseded by DDR2 SDRAM, DDR3 SDRAM, DDR4 SDRAM and DDR5 SDRAM. None of its successors are forward or backward compatible with DDR1 SDRAM, meaning DDR2, DDR3, DDR4 and DDR5 memory modules will not work in DDR1-equipped motherboards, and vice versa.
DDR SDRAM - Wikipedia